光学4f系统的图像空间频率特性

为将光学小波变换应用于图像压缩,分析光学4f系统中图像实现方式和图像采集对图像空间频率特性的影响,研究图像频域能量集中特性及其在光学4f系统中的表现,提出光学4f系统中图像空间频率特性的相关计算方法。理论分析、仿真计算和光学实验结果表明:用于图像压缩的光学小波变换在频谱面上的空间滤波范围受到输入图像尺寸、近轴条件、光学4f系统的器件采样特性、图像频域能量集中度以及系统噪声的影响,应根据实际光学4f系统选择合适的光学小波变换的空间滤波范围。实验结果验证了方法和结论的正确性。

Spatial frequency characteristics of optical 4f system

To achieve image compression with an optical wavelet transform method,we investigated the effects methods of image realization and image capture in an optical 4f system on the spatial frequency characteristics,and studied the characteristics of image energy concentration in the frequency domain of optical 4f system.The relevant calculation methods were thus proposed.The theoretical analysis,simulation and optical experimental results demonstrate that the spatial filtering radius of optical wavelet transformation,which can be applied to image compression,is controlled by various factors.These include the input images size,the adaxial condition,the apparatus sampling characteristics in an optical 4f system,the image energy concentration characteristics in the frequency domain,and the system noise.Thus,the suitable spatial filtering radius should be chosen according to the situation of actual optical 4f system.The methods and conclusions are verified by experimention.